Apparatus for casting steel roixb



E. H. MEBS APPARATUS FOR CASTING STEEL ROLLS Original Filed May 22, 1945 2 Sheets-Sheet 1 FIEA.

FIG. 1-

Dec. 27, 1949 E APPARATUS FOR'CASTING STEEL ROLLS Original Filed May 22, 1945 2 Sheets-Sheet 2 Mike-27, 1949 Irwinll.

lute-Illinois olNew-Iersey.

H ll Ohio. assignmto Car- Steel Corporation, a

Original No. 2.431.879. dated z, 1941, Serial No. 595,091, May 22. 1945. Application ior reissue June 21, 1039 Serial No. 100,501

2 cm (cl. 22-1341 Hatter enclosed in heavy brackets I II appears in the original patent but forms no part oi this reissue specification: matter printed in italics indicates the additions made by break adjacent the top portion of the casting-- while in hot condition.

Another object is to provide a method and apparatus tor casting ferrous metal articles in such mannerthat there is provided during the casting operation a localized plane of weakness in a predetermined plane whereby it breakage or cleavage takes place during the solidification oi the casting, it will occur at or closely adjacent to said predetermined plane of weakness.

A further object of the invention is to provide a method of casting ferrous metal objects in such manner that during solidification of the metal a zone of weahiess is maintained at a predetermined p lane below the iiuid metal so as to localize the tendency to form hot tears at said localized zone of w.

For a more complete understanding of the invention. reference should be made to the following detailed disclosure. the accompanying drawings, and the appended claims.

In the drawings:

Figure 1 is a longitudinal section through a novel form of apparatus for carrying out the herein claimed method.

Figure 2 is a cross section on line lIII of Figure 1.

Figure 3 is a cross section on line III-III Figure 1.

Figure 4 is an elevational view of a mill roll cast according to the teachings of the present invention.

Referring more particularly to the drawings, Figure 1 represents a vertical elevation of one half 01' the mold. The complete mold consists of two duplicate flask sections 'llll suitably secured in assembled relation, each section hav me a body of mold material therein such as highly bonded silica sand. indicated at It, the mold cavities being formed either-by the use of a conventional split pattern or by the conventional sweep method. While not limited thereto, the present invention is well suited for the casting of iron or steel rolling mill rolls or heavy pinions. By way of example, I have shown in Figure 4 a rolling mill roll having an intermediate roll portion ll of an enlarged diameter, a lower neck-portion ll of smaller diameter. and an upperneck portion ll of a diameter smaller than the portion It. In casting such articles in upright position, a problem occurs which is occasioned by the tendency of drastic chilling action to cause the formation of hot tears in the upper region of the article. As will appear more fully hereinafter, under my invention I provide a method and means wherein a zone of weakness is provided such as indicated at 20 in Figure 4, above the upper end 011 the casting ultimately produced. Above this zone of weakness in the formation of the casting there is produced a portion indicated at 21 which is normally cropped oil and discarded.

In the practice of the invention, the mold ior producing rolling mill rolls or pinions is provided with an intermediate mold cavity-2i of relatively large diameter which at the bottom opens into a cavity 01' smaller diameter, indicated at 25, and which at the top opens into a cavity of smaller diameter 28. Surrounding the intermediate cavity ll. of large diameter I provide a plurality of metal rings ill which serve to chill the molten metal during the casting operation.

Above the upper cavity 28 I provide a riser cavity II. It is apparent from the drawings that the cavities 2t and 28 correspond to the lower and upper reduced diameter neck portions It and it of the roll, shown in Figure 4, and that the catity 24' corresponds to the roll body portion ll of enlarged diameter of Figure 4. Similarly, the riser portion 32 or the mold corresponds to the portion 22 of Figure 4. e

A particular and essential feature of the here,- in claimed invention relates to the method and means for creating the zone of weakness in the article during the casting thereof. This is ac complished by incorporating in the mold means such as indicated at It, for forming a restricted orifice 3B in a" predetermined plane between the upper mold cavit 28 and the riser cavity 32.

. The means may be in the nature of a disc or slab of any material of suflicient strength and refractoriness, seated in an annular groove or trench formed in the mold. The disc-like member I may be made of kiln-dried fire clay either in a single disc-like perforated piece, or it may be formed of a plurality of arcuate segments. The means It which provides the restricted orifice fitsin a trench ll, isheld in place by the sand, and projects a definite predetermined distance (marked X) inwardly into the region between the mold cavity 28 and .the riser cavity 32.

The mold is formed with an upright vertical gate 40, and at the top is equipped with a' runnet cup 42 having a fiared'opening it into which sans the molten metal is teemed from a suitable ladle.

Asbestshowninl'lgure3,thebottomofthe' gate has a laterally extending portion 48 which connects tangentially with the lower mold cavity 20. In casting rolls or pinions according to my improved method, the ladle of molten metal is stationed directly above the runner cup 42 and the stopper of. the ladle raised te permit the stream of molten metal to enter the runner cu in the usual manner. The stream of molten metal therefore flows through the gate 40. The pouring rate is maintained relatively slow until the mold cavity 2 is filled approximately to the level of the tangential entrance 4. Thereupon the pouring ladle nozzle is opened wide and the full stream is permitted to enter the mold through the gate. The metal first rises through the lower cavity II and the intermediate cavity II in the mold with a spinning motion due to the tangential entry. Any dirt or foreign matter picked up by the stream of rising molten metal is retained in the center of the mold due tothe cupping effect and centripetal action, the dirt or foreign matter being lighter than the metal. As the top surface of molten metal rising within the mold approaches the means 34 incorporated in the mold, the spinning action is materially decreased. Therefore when the metal rises through the restricted orifice 38 over the means 34 and proceeds to fill the riser cavity 31, advantageously there is very little action due to trapped air and no formation of vacuum.

Immediately following the pouring of the mold, steps are preferably taken to keep the metal in the riser cavity 32 molten so that there will be a sufiicient storage of liquid metal for a considerable period of time, to feed the casting metal properly. This may be accomplished by covering the metal in the riser portion with a finely powdered exothermic material or with aninsulating medium, or by the incorporation of carbon rods horizontally across the mold about midway of the riser portion or by the addition of extra hot molten metal at frequent intervals.

A problem overcome by the invention is the prevention of hot tears such as frequently occur in the top parts of large articles cast in vertical upright position. In such upright cast articles there is always danger of cracks or hot tears forming at the stage when the metal is at the tender condition known to occur at a temperature of approximately 2350 F. Heretofore hot tearing has been particularly noticeable in the region corresponding to the upper roll neck It of Figure 4. It is believed to be caused by some sort of holding action within the mold, and

I have determined that when castings of this kind solidify in vertical position there is a very considerable linear contraction amounting to as much as 1'; of an inch per foot. The metal must be free toshrink. If the gate at the bottom or a fin at the top holds the metal as it solidifies at such locations, the casting is not permitted to contract freely as it freezes and therefore it is amenable to the formation of hot tears. This tendency to hot tearing is particularly noticeable in the casting of rolling mill rolls which are desirably chilled at the large diameter intermediate portion. By theuse of like disc 34 restricts the formation of hot tears to a definite predetermined zone of weakness in the region of the said means 84 having the restricted orifice II therein. By holding the metal during the solidification I refer to the restraint of the natural contraction caused by adhesion of the casting surface to the surrounding compacted sand of the mold. Such restraint or holding of the metal is accentuated by the chills which cause a very rapid cooling and rapid contraction of one portion of the casting while another Portion thereof is in a semi-plastic state. This holding action is particularly noticeable where said semi-plastic portion is of reduced cross section. It is clear, therefore, that the invention provides for confining the region of hot tearing to a definite and predetermined zone, thus insuring that the working parts of' the casting are thoroughly sound and homogeneous. The creation of the zone of weakness has the added advantage of providing means for breaking off the cropped portion 22 formed in the riser cavity 12 of the mold.

While I have described quite precisely a specific mold and a casting procedure which an actual reduction to practice has demonstrated to be highly desirable, it is not to be construed that I am limited thereto, since various modifications may be made by those skilled in the art within the scope of the appended claims.

I claim:

1. In a mold for casting steel rolls including a bonded sand body and chill members, said sand body having an upright cylindrical cavity of relatively large diameter in which the roll body is formed, top and bottom cavities of smaller diameter at the ends of said first named cavity in which the roll necks and stock for the wobblers are formed, said top cavity being of uniform diameter, a tangential gate passage for introducing molten metal to said bottom cavity, and a riser above said top cavity, said chill members being embedded in said sand body amound said first named cavity, a device for localizing hot tears in a casting formed in the mold to a region outside the casting proper between said top cavity and said riser, said device comprising an orifice forming disc-like transverse ring supported in said sand body between said top cavity and said riser and projecting a predetermined distance into the mold cavity, the distance of projection of said ring providing a diameter opening through the ring only slightly less than the diameter of said top cavity, whereby said ring creates a plane of weakness between the casting proper and the riser but does not stop flow of foreign material into the riser.

2. In a mold for casting steel rolls includingbody is formed, top and bottom cavities of my improved mold and in following the method 7 steps of my invention, the chill within the mold serves as a means for holding the metal during smaller diameter at the ends of said first named cavity in which the roll necks and stock for the wobblers are formed, said top cavity being of uniform diameter, a tangential gate passage for introducing molten metal to said bottom cavity, and a riser above said top cavity, said chill memhere being embedded in said sand body around said first named cavity, a device for localizing hot tears in a casting formed in the mold to a region outside the casting proper between said top cavity and said riser, said device comprising an orifice forming disc-like transverse ring sup- 5 ported in said sand'body between said top cavity and said riser at the crop-on plane and projectinn a predetermined distance into the mold cavity, the distance of projection of said ring providing a diameter opening through the ring only slightly less than the diameter of said top cavity, whereby said ring creates a plane of weakness between the casting proper and the riser but does not stop flow of foreign material into the riser.

ERWIN H. MEBS.

REFERENCES CITED The following references are of record in the ale 0: thlspatent or of the original patent.

UNITED STATES PATENTS Number Name Date 900,970 Washbum Oct. 13, 1908 969,015 Washburn A118. 30. 1910 1,071,809 Seaman Sept. 2. 1913 1,658,834 Daniels et al. Feb. 14, 1928 2,294,169 Francis et al Aug. 25, 1942 2,377,731 Walcher June 5, 1945 OTHER REFERENCES Metal Industry. December 27, 1946, pagu 533 and 534. 

